Omission

noun

1. The act of omitting.
2. The act of neglecting to perform an action one has an obligation to do.
3. Something deleted or left out.

   "The suspicious omissions in the new edition of the book attracted claims of censorship."

4. Something not done or neglected.
5. (grammar) The shortening of a word or phrase, using an apostrophe ( ' ) to replace the missing letters, often used to approximate the sound of speech or a specific dialect.